--- /dev/null
+Microchip MCP2308/MCP23S08/MCP23017/MCP23S17 driver for
+8-/16-bit I/O expander with serial interface (I2C/SPI)
+
+Required properties:
+- compatible : Should be
+ - "mcp,mcp23s08" (DEPRECATED) for 8 GPIO SPI version
+ - "mcp,mcp23s17" (DEPRECATED) for 16 GPIO SPI version
+ - "mcp,mcp23008" (DEPRECATED) for 8 GPIO I2C version or
+ - "mcp,mcp23017" (DEPRECATED) for 16 GPIO I2C version of the chip
+
+ - "microchip,mcp23s08" for 8 GPIO SPI version
+ - "microchip,mcp23s17" for 16 GPIO SPI version
+ - "microchip,mcp23008" for 8 GPIO I2C version or
+ - "microchip,mcp23017" for 16 GPIO I2C version of the chip
+ NOTE: Do not use the old mcp prefix any more. It is deprecated and will be
+ removed.
+- #gpio-cells : Should be two.
+ - first cell is the pin number
+ - second cell is used to specify flags. Flags are currently unused.
+- gpio-controller : Marks the device node as a GPIO controller.
+- reg : For an address on its bus. I2C uses this a the I2C address of the chip.
+ SPI uses this to specify the chipselect line which the chip is
+ connected to. The driver and the SPI variant of the chip support
+ multiple chips on the same chipselect. Have a look at
+ microchip,spi-present-mask below.
+
+Required device specific properties (only for SPI chips):
+- mcp,spi-present-mask (DEPRECATED)
+- microchip,spi-present-mask : This is a present flag, that makes only sense for SPI
+ chips - as the name suggests. Multiple SPI chips can share the same
+ SPI chipselect. Set a bit in bit0-7 in this mask to 1 if there is a
+ chip connected with the corresponding spi address set. For example if
+ you have a chip with address 3 connected, you have to set bit3 to 1,
+ which is 0x08. mcp23s08 chip variant only supports bits 0-3. It is not
+ possible to mix mcp23s08 and mcp23s17 on the same chipselect. Set at
+ least one bit to 1 for SPI chips.
+ NOTE: Do not use the old mcp prefix any more. It is deprecated and will be
+ removed.
+- spi-max-frequency = The maximum frequency this chip is able to handle
+
+Optional properties:
+- #interrupt-cells : Should be two.
+ - first cell is the pin number
+ - second cell is used to specify flags.
+- interrupt-controller: Marks the device node as a interrupt controller.
+NOTE: The interrupt functionality is only supported for i2c versions of the
+chips. The spi chips can also do the interrupts, but this is not supported by
+the linux driver yet.
+
+Optional device specific properties:
+- microchip,irq-mirror: Sets the mirror flag in the IOCON register. Devices
+ with two interrupt outputs (these are the devices ending with 17 and
+ those that have 16 IOs) have two IO banks: IO 0-7 form bank 1 and
+ IO 8-15 are bank 2. These chips have two different interrupt outputs:
+ One for bank 1 and another for bank 2. If irq-mirror is set, both
+ interrupts are generated regardless of the bank that an input change
+ occurred on. If it is not set, the interrupt are only generated for the
+ bank they belong to.
+ On devices with only one interrupt output this property is useless.
+- microchip,irq-active-high: Sets the INTPOL flag in the IOCON register. This
+ configures the IRQ output polarity as active high.
+
+Example I2C (with interrupt):
+gpiom1: gpio@20 {
+ compatible = "microchip,mcp23017";
+ gpio-controller;
+ #gpio-cells = <2>;
+ reg = <0x20>;
+
+ interrupt-parent = <&gpio1>;
+ interrupts = <17 IRQ_TYPE_LEVEL_LOW>;
+ interrupt-controller;
+ #interrupt-cells=<2>;
+ microchip,irq-mirror;
+};
+
+Example SPI:
+gpiom1: gpio@0 {
+ compatible = "microchip,mcp23s17";
+ gpio-controller;
+ #gpio-cells = <2>;
+ spi-present-mask = <0x01>;
+ reg = <0>;
+ spi-max-frequency = <1000000>;
+};
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